The E2/M1 ratio in {Delta} photoproduction
- Brookhaven National Lab., Upton, NY (United States). Physics Dept.
- Univ. of South Carolina, Columbia, SC (United States). Dept. of Physics
- Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Physics Dept.; and others
The properties of the transition from the nucleon to the {Delta}(1232) serve as a benchmark for models of nucleon structure. To first order, N {r_arrow} {Delta} photo-excitation is dominated by a simple M1 quark spin-flip transition. At higher order, small L = 2 components in the N and {Delta} wavefunctions allow this excitation to proceed via an electric quadrupole transition. Since Nucleon models differ greatly on the mechanisms used to generate these L = 2 components,, the ratio of E2/M1 transitions (EMR) provides a sensitive test for structure models. Here, new high-precision measurements of p({rvec {gamma}}, {pi}) and p({rvec {gamma}}, {gamma}) cross sections and beam asymmetries have been combined with other polarization ratios in a simultaneous analysis of both reactions. Compton scattering has provided two important new constraints on the photo-pion amplitude. The E2/M1 mixing ratio for the N {r_arrow} {Delta} transition extracted from this analysis is EMR = {minus}3.0% {+-} 0.3 (stat+sys) {+-} 0.2 (model).
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 642742
- Report Number(s):
- BNL-64648; CONF-970526-; ON: DE98000315; TRN: 98:009922
- Resource Relation:
- Conference: International conference on quark lepton nuclear physics (QULEN): Nonperturbative QCD hadron physics and electroweak nuclear processes, Osaka (Japan), 20-23 May 1997; Other Information: PBD: Aug 1997
- Country of Publication:
- United States
- Language:
- English
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The E2/M1 ratio in {Delta} photoproduction
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